The intervals between oral-THC maintenance sessions allowed cannabis smoking. Describing those intervals as drug-free washouts would misstate the study’s exposure history.
The full schedule matters
Eleven daily cannabis smokers lived on a research unit for 51 days. Four five-day maintenance sessions used placebo or 30, 60 or 120 mg oral THC per day. Each was separated by nine days during which ad-libitum cannabis smoking was permitted at specified times.
The fifth day of each maintenance session also included a controlled five-puff smoked-cannabis challenge. Oral-fluid and plasma ratios were therefore observed against a structured history of both oral administration and prior or concurrent smoking.
An interval does not necessarily eliminate exposure
A washout intended to remove prior drug differs from an interval that deliberately allows further use. Residual cannabinoid findings at the next session are not automatically evidence of unauthorized exposure. Here, the permitted smoking history was part of the protocol and part of the reason baseline measurements mattered.
Limits on transferring the result
The design helps investigate maintenance and renewed smoking in established users. It cannot be treated as a series of first-ever oral doses in previously unexposed people. When applying a ratio to another case, preserve the preceding exposure schedule rather than assuming a clean baseline from the number of days between experimental conditions.
Related reading: limits of identifying cannabis sources.
Research cited
Lee and colleagues (2013). Oral fluid/plasma cannabinoid ratios following controlled oral THC and smoked cannabis administration. DOI: 10.1007/s00216-013-7159-8.
Leave a Reply